1. Field of the Invention
The present invention relates to control of a fluid power generator.
2. Description of the Related Art
For reduction of carbon dioxide, power generations by utilizing natural energies, such as wind power generation, hydraulic power generation, and photovoltaic power generation, have been attracting a great deal of attention. Enhancement of the efficiency of such natural energy power generations is of great importance to solve the environmental problems.
A fluid power generator may be constructed, for example, with a brushless motor structure. One example of the brushless motor structure is disclosed in JP 2001-298982A.
One typical example of the fluid power generator is a wind power generator. The wind power generator uses blades that receive the wind force to rotate. The blades are generally designed to have a large weight for the enhanced inertia of rotation. In the condition of low wind force, it is difficult to rotate the blades and start power generation. One proposed structure of the wind power generator uses a drive motor separate from the power generator to start rotation of the blades even in the condition of low wind force.
This prior art structure, however, requires the separate drive motor for starting the power generator. This undesirably complicates the overall mechanism and increases the manufacturing cost. Such drawbacks are not characteristic of the wind power generator but are commonly found in various fluid power generators.